Patent GB-222991-A (GB)
Title: Improvements in and relating to gyroscopic stabilizing systems
IPC: G05D1/08
Filed: 1923-07-21
Abstract: 222,991. White, A. E., (Sperry Gyroscope Co.). July 21, 1923. Alternating - current induction machines; motors, controlling.-In apparatus for stabilizing ships, in which precession of a stabilizing gyroscope is produced by an electric motor geared to the gyro-casing, the motor is adapted to brake the gyroscope at each end of its precessional cycle, and operates regeneratively to assist in driving the gyro-motor. Fig. 3 shows diagrammatically one arrangement. The gyro-rotor is driven by a three-phase motor 9, 10 driven by an alternating-current generator 27 forming part of a generator set consisting also of a directcurrent motor 28 and a generator 25 having opposed field windings 23, 24. The precession motor 12 is a direct-current machine, the direction of rotation of which is controlled by an auxiliary gyroscope 15 mounted in the known manner to process in response to rolling of the ship, and provided with a contact-arm 16 adapted to close a circuit through one or the other of contacts 17, 18 to energize one or other of the windings of the generator 25, with which the motor 12 is normally in circuit. Included in the circuits of the windings 23, 24 are electromagnet coils 29, 30 adapted to attract an armature 31 to close the circuit through the machines 12, 25. The motor 12 has a separately-excited field 33 and also an additional field winding 38, the cir. cuit of which is initially kept open by a coil 34 attracting an armature 35 away from a contact 36. As the speed of precession increases the armature 35 is pulled on to the contact 36 by a spring 37, the field of the motor 12 being thereby strengthened to limit the speed of precession and to cause the motor to act regeneratively to assist in maintaining the speed of the motor 9. When the angle of precession approaches its maximum a contact-arm 39 on the gyroscope comes into contact with one of the two fixed contacts 42, 43 and closes a circuit through a coil 48 or 49 which attracts the corresponding armature 21 or 22 and breaks the field circuit of the generator 25 and also the circuit of the coil 29 or 30. At the same time a circuit is closed through one of the coils 44, 45 to attract the armature 31 on to a contact 46, thus breaking the circuit through the machines 12, 25 and closing a circuit through the machine 12, 28. The motor 28 has a low resistance and a low counter E.M.F., so that the machine 12, being driven as a generator by the precession of the gyroscope, will cause a large current to pass through the circuit and thus the gyroscope will be braked and brought to rest. Fig. 4 shows a modification in which the precession motor 12<1> is a three-phase machine, the field of which is energized by the generator 27<1> through a pivoted reversing-switch 52 operated by coils 53, 54, the circuits of which are controlled by the auxiliary gyroscope 15<1>. The field winding 90 of the motor 12<1> is arranged so that the current through a part 91 can be reversed to vary the number of poles in the winding, the direction of this current being controlled by a pivoted switch-arm 59 which is biassed by springs 63, 63<1> towards contacts 62, 61', corresponding to the larger number of poles. When the gyroscope 15<1> precesses to bring the arm 16<1> against, say, the contact 17<1> the circuit of the coil 53 is closed to energize the winding 90. At the same time a circuit is closed through the coil 64 which attracts the switch 59, against the action of 'the springs 63, 63<1> and dashpots 66, 66<1> to complete a circuit through the contacts 61, 62' with consequent diminution of the number of poles in the winding 90, the motor 12' being thus caused to act regeneratively and to brake the precession. When the angle of precession is such that an arm 67 on the gyroscope makes contact with one. of the contacts 74, 75, a circuit is closed through the coil 70 or 70', and the armature 71 or 71<1> is attracted to short-circuit the coil 64 or 65 so that the switch 59 is again move'd on to the contacts 62, 61<1> to increase the number of poles in the winding 90, the braking effect of the motor 12' being thus increased. When the gyroscope approaches the limit of its precession the arm 67 makes contact with one of the contacts 74, 75 to close a circuit through the coil 76 or 76<1> which attracts an armature 77 or 77', thereby breaking the field circuit of the precession motor. At the same time a solenoid 79 is energized to operate a mechanical brake to stop the motor.